Field of the Invention
The present invention relates to a winding apparatus suitable for winding a web material, comprising a first and a second side and a free end, onto an empty core and into a roll, the winding apparatus comprising a winding drum for guiding the web material by supporting it on the first side, and further comprises cutting means for cross-cutting the web material prior to it being wound onto an empty core. The winding apparatus also comprises means for moving the empty core from a first position to a second position comprising a set of retainer arms for carrying and moving the core from the first position to the second position near the periphery of the winding drum while web material is being wound onto the core, and for carrying at least one roller that is arranged to lift the web material from the winding drum, during winding, prior to cross-cutting said web material along said roller and thus creating said free end of web material.
Description of Related Art
It is well known to wind different types of webs, e.g., plastic foil or film, paper and other types onto a center roll—a core—made from, e.g., metal, plastic or paper. Also, a core bar, a winding shaft or the like can be used, but in the following text the term “core” will be used as a common term for all the different types of cores and shafts. Such winding processes are performed with high speed, and when one roll is full, the web has to be cut and guided to a new and empty core. In order to attach the web to the core, it is common to add an adhesive to the surface of the roll, for example, either as a hot melt adhesive or preferably as a tape that is attached to the cores and also has an adhesive side facing the web that has to be wound. Web material will typically be wound onto a core during production, and e.g., plastic foil or film will be produced using an extruder and the foil or film will be wound immediately after it leaves the extruder. However, it is common to cut the foil or film into specific widths prior to winding it.
Hot melt or other types of adhesives have a number of drawbacks that make alternative solutions attractive. First of all, it can be difficult to control the hot melt and often the hot melt adhesive will/can be absorbed into the web, and then, several layers of the web material are glued together so as to be of no use, and therefore, must be considered as waste. This is also a known problem when using other types of adhesive. Further, a foil or film that has been glued to the core can block the equipment where the web is being unwound since, if the web sticks to the core, the web might burst which might lead to the equipment being jammed or even damaged by several layers of web material and adhesive being pulled into the equipment.
Another solution that is very common is to add an adhesive tape—often a polypropylene tape—to the core. It is then possible to attach the web to the core when winding the web onto the core, but the tape solution also offers a number of drawbacks. When a roll of web material is empty, the tape can have a tendency to be so strong that the web is broken or torn, thus exerting some unwanted forces onto the equipment. Further, the tape on the core tends to be pulled off from the core and to continue into the apparatus where the web material is processed. This is highly unwanted as the tape may easily damage or require the machinery to be stopped for either cleaning or repair. The tape is, as mentioned, normally made from polypropylene and is not recyclable unlike the paper core and this is another drawback. The tape also has the drawback that the innermost of the layers on the core often will be irregular or even bumpy due to the thickness of the tape. The tape can even have an overall influence on the regularity of the complete roll. If, e.g., a roll of thin plastic film does not have a very even and circular shape, the complete roll can only be sold as a second grade roll, which of course has a negative impact on the price. Adding the tape to a typical paper core is further time consuming and, as a consequence, also expensive.
It is thus very important to be able to wind web material onto a core without the need for adding tape to the core and preferably without use of any other processes that will prevent the web from being unwound until the very last centimeter and without creating a huge amount of waste, and especially waste which is not recyclable.
None of the above known solutions address the above problems, and so far the problem might have been realized, but no solution is given.